#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#define M 10
float Get_average(int arr[], size_t x)
{
	int sum = 0;
	for (int i = 0; i < x; i++)
	{
		sum += arr[i];
	}
	return sum / x;
}
int main()
{
	int arr[M];
	for (int i = 0; i < M; i++)
	{
		scanf("%d", &arr[i]);
	}
	printf("%f", Get_average(arr, 8));
	return 0;
}